Generally speaking, satellites are launched into earth orbit for various applications relating to terrestrial, nautical, aeronautical, civil, and commercial communication, navigation, exploration, and observation, scientific research, and others. The satellites transmit radio frequency (RF) signals related to their operations. The satellite RF signals may be collected, interpreted, and processed by terrestrial satellite transceivers (transmitter/receivers) operable for exchanging signals with the satellites or other entities.
Communications satellites are operable for relaying information from a transmission source to transceivers in telecommunication related applications. Global communication networks and services may be provided, sustained, and supported by a communication satellite constellation, which comprises a plurality of individual communication satellites. Communication networks are operable with the satellite constellations to provide global telephone and data services of various kinds to users of portable and/or mobile transceiver terminals.
The portable/mobile transceiver terminals comprise antenna components, with which they may connect and exchange signals with the satellites. One or more terrestrial ground stations may participate in the communications. The communications may relate to messages and other traffic with which assets may be tracked and monitored, which may be moved in commerce or other endeavors.
Satellite terminals installed on the tracked assets support the messaging, tracking, and monitoring. For example, the SAT-202™ satellite terminal Satellite terminal (commercially available from the Honeywell Global Tracking™ subsidiary of Honeywell International™, Inc., a corporation in New Jersey) comprises a multi-purpose satellite terminal that may be installed on tracked assets. The SAT-202™ terminals are operable for automatically selecting an available satellite within a satellite constellation, and regularly transmitting its location, telemetry data, and message data thereto over wireless data links.
Satellite transceivers comprise an antenna operable as an interface for exchanging RF signals with the communication satellites. The SAT-202™ transceiver terminals exchange signals with the satellites over the L-Band between one Gigahertz (1 GHz) and two (2) GHz (inclusive) of the RF spectrum. The transceiver may comprise a patch antenna, which may achieve circular polarization by quadrature excitation of two linearly polarized ports. For example, the SAT-202 satellite transceiver comprises an L-band patch antenna with circular polarization that provides significant gain over low elevation angles and a frequency range spanning 1525 Megahertz (MHz) to 1661 MHz, inclusive.
Typically, antennae used in the satellite transceivers are enclosed within a radome and comprise two or more printed circuit board assemblies (PCBAs). The radomes typically comprise a weather resistant plastic material, which is transparent over the antenna RF range. The PCBAs comprise one or more electronic components disposed over a printed circuit board (PCB), which comprises a dielectric substrate and a network of conductive horizontal traces and/or vertical interconnect accesses (“vias”). The PCBAs, the PCB substrates thereof, and the attachment of the plastic radome during assembly of the antenna represent nontrivial expenses, which are typically reflected in the cost of the satellite transceivers.
For example, patch antennae in typical satellite transceivers may comprise internal coaxial cable couplers, as well as circuit components operable for the quadrature excitation of two linearly polarized ports to achieve circular polarization. In some transceivers, the polarizing circuit components may be disposed on a dedicated PCB, with associated cost and fabrication complexity issues. The quality of the circular polarization may be sensitive to the fabrication issues, and cross-polarization near the horizon may approach excessive levels. Left-hand polarization associated with this effect may cause signal fading at low elevation angles.
Therefore, a need exists for a satellite transceiver antenna that provides significant gain over a wide angle from an axis of maximum radiated power, and over a wide range of terrestrial locations world-wide for exchanging signals from geostationary communication satellites. A need also exists to implement the satellite transceiver antenna with right-hand circular polarization and to avoid interference associated with left-hand polarization. Further, a need exists to reduce complexity and costs related to components and fabrication of the satellite transceiver antenna, relative to existing conventional approaches.